Crossword Genius

Passing a red light is no such success! (6)

Ross

I believe the answer is:

signal

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'passing' is the definition.
Both the answer and definition are adjectives. Maybe you can see an association between them that I can't see?

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for signal that I've seen before include "Notable; warning sign" , "Remarkably good or bad; transmit (message)" , "Nonverbal action or gesture that encodes a message" , "Gesture, light or sound which sends a message" , "Sign that conveys a message" .)

I've seen this clue in the Evening Standard.
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